1. Field of the Invention
The invention relates generally to integrated circuits (IC) and more particularly to systems and methods for shifting the common mode voltage of a signal passing from one power domain in the IC to another.
2. Related Art
As digital devices (e.g., integrated circuits) have become more complex, and operate at ever increasing speeds. The complexity of the devices has been manifested in many ways, including the implementation of designs incorporating regions of circuitry that have different power requirements. For example, some circuits combine analog and digital components, where the analog circuits typically operate at a higher voltage than the digital circuits.
There is often a need to transfer data between domains. When transferring data or signals between domains, the signals have to be adjusted so that they have the appropriate characteristics for the destination domain. The distribution of clock signals is one such example. Signals such as clock signals must be passed between the components of different power domains, and must therefore cross the boundaries of the different domains. The signals may therefore need to be modified to suit the destination domain.
When translating a signal from a domain which uses a first supply voltage to a domain that has a different supply voltage, it is typically necessary to shift the common mode voltage of the signal from the level of the originating domain to that of the destination domain. This is commonly referred to as level shifting. There are conventional schemes for performing level shifting, but the devices that are typically used to implement these schemes are not suitable for performing this task at the frequencies required of contemporary systems.
It would therefore be desirable to provide systems and methods for level shifting that do not suffer from conventional devices' inability to operate at higher frequencies.